Dynamic control of lance utilizing counterflow fluidic techniques

ABSTRACT

A jet of gas injected from a lance is fluidically deviated with a gas flowing in either the same or opposite direction as the jet of gas. The gas used to fluidically deviate the jet is the same as or different from the gas in the jet.

CROSS-REFERENCE TO RELATED APPLICATIONS

None.

BACKGROUND

There are a variety of industrial applications utilizing injection of ajet of gas into a reaction space.

One application is a non-ferrous metallurgical furnace. It is known toprovide a layer of liquefied inert gas such as Argon over a bath ofmolten for the purpose of avoiding the pickup of oxygen from theatmosphere above the bath. The Argon is typically introduced above thebath as a stream of liquefied gas. The liquefied gas pools above thebath and vaporizes to produce an expanding gas which drives out anyoxygen above the surface of the bath. Typically, the Argon is introducedabove the bath using a fixed lance. While the prior art methods haveprovided a fairly satisfactory solution, such methods utilizing a fixedlance do not achieve maintenance of a uniform layer of liquefied gasabove a large area of the bath while at the same time avoidingoverconsumption of the Argon.

Some non-ferrous processes utilize oxygen for refining. An example isthe refining of copper. Copper is inert relative to other metals sooxygen and/or air can be used to oxidize dissolved elements. Oxygenand/air can also be used to impart the correct amount of dissolvedoxygen for certain applications such as copper rod. Non ferrous bathsoften have a large surface area that would normally be poorly mixed. Amoveable lance would provide more uniform application of oxygen and/orair.

Another application is a furnace, including electric arc furnaces(EAFs). In electric arc furnaces, the materials to be melted areintroduced at the top of the furnace. Depending on several parameters astype of raw materials (pig iron or scrap iron or steel), size of thefurnace, etc, the EAF may be equipped with burners delivering a power ofseveral megawatts. This combustion of fuel (mainly natural gas butsometimes fuel-oil) with oxygen brings heat to initiate melting of thescrap. The scrap in front of the burners is heated first. The burnermust have a high momentum flames for at least a few reasons. First, highmomentum flames are needed to avoid the deviation of the flame towardsthe walls or even towards the burner panel. Second, they are needed toquickly create a cavity in the scrap pile thereby increasing heattransfer efficiency. Third, they are needed to avoid clogging of theinjectors by steel droplets once the scrap is melted and transformedinto liquid steel (thus, a low power flame is always on).

A cutting operation in the electric arc furnace occurs during the scrapmelting phase when the scrap is hot but not molten. In this phase, heattransfer between oxy-fuel burner flame and the scrap is no longerefficient so final melting in the “cold spots” is performed using oxygenand the mechanism of heating is chemical energy provided by the oxygenreacting with the scrap. Cutting is used normally by operating oxy-fuelburners with excess oxygen or by using the door lance through the slagdoor.

A refining operation in an electric arc furnace deals with the removalof primarily carbon, but also phosphorus, sulfur, aluminum, silicon andmanganese from the steel. Typically, refining operations are carried outonce the steel scrap is completely melted and involves oxidation of theabove mentioned impurities through injection of a supersonic oxygen jetinto the molten bath. Removal of carbon impurities is referred to as thedecarburization process, a process which occurs in the steel bath and ina slag-gas-steel emulsion after the burner operation is stopped. Therefining step in the EAF is also called the “hard lance mode”. Itincludes reactions between C (coal particles and dissolved carbon in themelt), CO, CO₂ and O₂ which provided by the supersonic lance. Theoxidation of carbon generates CO bubbles that can flush from the bathdissolved gases such as hydrogen and nitrogen, which are also recognizedas a concern. The injected oxygen also lowers the bath carbon content tothe desired level for tapping. Because most of the other non-carbonimpurities during refining have a higher affinity for oxygen thancarbon, oxygen preferentially reacts with these elements to form oxideswhich can be removed in the resultant slag.

The location of an EAF tool such as a burner or lance can be describedby the distance of the tool from the nominal steel bath surface. Thelance is typically located a distance of 0.5 to 2 meters above the steelbath. A foaming slag (CO bubbles), created by the carbon-oxygen reactionduring carbon injection, floats on the steel bath. In most EAFs, aburner and a supersonic lance are combined into a single multifunctiontool. The implementation of such a tool depends mainly on the furnacetype, the composition and quality of the raw materials. The angle ofinjection (with respect to horizontal) of the supersonic O₂ jet is oftenaround 40-45° from the horizontal. However, this value can be as high as50° and it will depend upon the construction of the furnace. Onceinstalled to a furnace, many supersonic lances for EAFs currentlyavailable in the market inject oxygen into the bath at a fixed angle.This fixed angle present several limitations. The fixed location ofimpact of the supersonic jet locally depletes the carbon content in theimpact area. As, a result, FeO generation in the immediate vicinity ofthe impact point is relatively high. FeO is very corrosive to furnacerefractories, so excessive refractory damage at this location is common.Second, due to certain technical constraints, many lances have to belocated at a distance higher than optimal above the steel bath surfaceto achieve the often optimal 40-45° angle of injection. This is becausethe jet must be tilted more downwardly toward the steel. Third, fixingthis angle has the effect of fixing the area of the steel bath surfacethat is targeted by the supersonic jet. If only a portion of the bathcan be stirred by impingement of the jet upon the targeted portion, theoverall refining reaction is limited by the relatively slow diffusion ofoxygen through the non-targeted/unstirred portions of the bath.Acceleration of the overall refining process thus often requires the useof multiple tools for separately targeting multiple portions of thebath. Fourth, apart from the stirring issue, a fixed angle of attacklimits the ability of the lance to generate a thick foamy slag on thebath surface over more than just the targeted area. This is importantbecause quick generation of thick, foamy slag across much of the bathsurface decreases the tap-to-tap time and increases furnaceproductivity. Speedier generation of the thick, foamy slag oftenrequires the use of several lances each one of which targets a specificportion of the bath.

As a result of the fixed angle, most of the existing supersonic lancesolutions are concerned with estimating an optimal number of lances anddetermining their optimal locations. While a more dynamic and adaptivecontrol may be achieved with the use of supersonic lances utilizingmoving parts, this approach is not a robust solution for supersonic jetsin the very dusty environments of EAFs because the moving parts areexposed to severe thermal, mechanical and chemical attacks.

Similar rationales can be applied to other steelmaking processes such asthe Basic Oxygen Furnace (BOF), the top and bottom mixed blowingconverter (QBOP), the Argon Oxygen Decarburisation (AOD) process and theVacuum Oxygen Decarburization (VOD) process.

Thus, there is a need in the art for providing a solution that overcomesthe above problems.

SUMMARY

There is provided a method of injecting a jet of a gas into an interiorof a reaction space containing a liquid or solid reactant. The methodincludes the following steps. A lance is provided that comprises a mainbody having a primary conduit and a secondary conduit formed therein andupstream and downstream ends. A jet of a gas is injected from the outletof the primary conduit and into the reaction space. A vacuum is appliedto the secondary conduit to create a counterflow of a gas into thesecondary conduit outlet from the reaction space interior and to causedeviation of the jet towards the counterflow. Each of the primary andsecondary conduits extends between a respective inlet and a respectiveoutlet, the outlets being disposed at the downstream end. An outlet ofthe secondary conduit is disposed at a location adjacent the primaryconduit outlet.

There is also provided a system for injecting a jet of a gas into aninterior of a reaction space containing a liquid or solid reactant. Thesystem comprises: a lance comprising a main body, a source of a firstgas, and a source of vacuum. The main body has a primary conduit and asecondary conduit formed therein and upstream and downstream ends. Eachof the primary and secondary conduits extends between a respective inletand a respective outlet, the outlets being disposed at the downstreamend. An outlet of the secondary conduit is disposed at a locationadjacent the primary conduit outlet. The source of the first gas is at apressure higher than ambient and it fluidly communicates with theprimary conduit. The source of vacuum is in selective fluidcommunication with the secondary conduit.

There is provided another method of injecting a jet of a gas into aninterior of a reaction space containing a liquid or solid reactant. Themethod comprises the following steps. A lance is provided comprising amain body having a primary conduit and a secondary conduit formedtherein and upstream and downstream ends. A jet of a first gas isinjected from the outlet of the primary conduit and into the reactionspace. A second gas is injected from the outlet of the secondary conduitto create a co-flow of the second gas adjacent to a peripheral region ofthe jet such that the jet is deviated towards the co-flow of second gas.The first and second gases are the same or different. Each of theprimary and secondary conduits extends between a respective inlet and arespective outlet, the outlets being disposed at the downstream end. Anoutlet of the secondary conduit is disposed at a location adjacent theprimary conduit outlet.

There is provided another system for injecting a jet of a gas into aninterior of a reaction space containing a liquid or solid reactant. Thesystem comprises: a lance comprising a main body, a source of a firstgas, and a source of a second gas. The main body has a primary conduitand a secondary conduit formed therein and upstream and downstream ends.Each of the primary and secondary conduits extends between a respectiveinlet and a respective outlet, the outlets being disposed at thedownstream end. An outlet of the secondary conduit is disposed at alocation adjacent the primary conduit outlet. The source of the firstgas is at a higher than ambient pressure and it fluidly communicateswith the primary conduit. The source of the second gas is at a higherthan ambient pressure and is in selective fluid communication with thesecondary conduit. The first and second gases are the same or different.The source of second gas is at a pressure higher than that of the sourceof the first gas.

There is also provided a lance for injecting a jet of a first gas intoan interior of a reaction space. The lance comprises: a main body havingupstream and downstream ends and primary and secondary conduits formedtherein; and a collar comprising a wall extending around the primary andsecondary conduit outlets from the main body downstream end. Each of theprimary and secondary conduits extends between an associated inlet andan associated outlet, each of the primary and secondary conduit outletsbeing disposed at the downstream end. A terminal portion of the primaryconduit at the downstream end extends along an axis. The primary conduitinlet is adapted to be placed in fluid communication with a source of afirst gas. The secondary conduit inlet is adapted to be placed in fluidcommunication with a source of vacuum or a source of a second gas. Aninner surface of the collar wall diverges away from the primary conduitaxis to define a vectoring space adapted to allow expansion of a jet ofthe first gas exiting the primary conduit outlet. The source of thefirst gas is the same as or different from the source of the second gas.The secondary conduit outlet is disposed at a location adjacent theprimary conduit outlet sufficient to fluidically deviate a jet of thefirst gas exiting the primary conduit outlet towards the collar innerwall surface adjacent the secondary conduit outlet when the secondaryconduit inlet is placed in fluid communication with either the vacuumsource or the source of the second gas.

Any of the disclosed methods, systems, or lance may include one or moreof the following aspects:

-   -   the jet has a velocity with a Mach number in a range of from 0.3        to 5.0.    -   the jetted gas is oxygen.    -   the jetted gas is oxygen-enriched air.    -   the jet is deviated by an angle θ with respect to the axis and θ        is in the range of 0°<θ≦45°.    -   said application of vacuum is discontinued such that the jet is        no longer deviated towards the counterflow.    -   said steps of applying and discontinuing application of the        vacuum are alternated such that the jet is swept along an area        described by an angle θ in the range of 0°<θ≦45°.    -   the lance has a plurality of secondary conduits each one of        which extends between a respective inlet and a respective        outlet, each of the secondary conduit outlets being disposed at        the downstream end, wherein application of vacuum is alternated        between the plurality of secondary conduits to alternatingly        deviate the jet towards different ones of the plurality of        secondary conduits.    -   alternating application of the vacuum between two of the        secondary conduits has the effect of sweeping the jet over an        angular deviation of from about −45° to about +45°.    -   the jet is supersonic.    -   the jet has a flow rate of 200 Nm³/h to 4000 Nm³/h.    -   a ratio of the static pressure of the counterflow to the static        pressure of the jet at the primary and secondary conduit outlets        is in a range of from 0.01 to less than 1.00.    -   the lance further comprises a collar extending from the        downstream end of the main body, the collar having a wall        extending around the primary and secondary conduit outlets, an        inner surface of the wall defining a vectoring space, wherein        the jet attaches to the inner surface adjacent the secondary        outlet when the vacuum is applied thereto.    -   the lance has n secondary conduits each one of which extends        between a respective inlet and a respective outlet, each of the        secondary conduit outlets being disposed at the downstream end,        wherein application of vacuum is alternated between the n        secondary conduits to alternatingly deviate the jet between a        respective n counterflows and n is an integer in the range of        from 2-6.    -   the jet is swept across a straight line-shaped target area.    -   the jet is swept across a triangular target area.    -   the jet is swept across a quadrilateral target area.    -   the reaction space is an electric arc furnace.    -   the reaction space is a molten bath of non-ferrous metal.    -   the source of the vacuum is selected from a vacuum pump, an        ejector pump, and a diverging portion of a converging-diverging        nozzle.    -   the jet is ideally expanded.    -   the jet is under-expanded.    -   the reaction space is a Basic Oxygen Furnace (BOF) or a top and        bottom mixed blown (QBOP) converter    -   the reaction space is an Argon Oxygen Decarburization (AOD)        furnace    -   the reaction space is a Vacuum Oxygen Decarburization (VOD)        furnace    -   the lance has a plurality of secondary conduits each one of        which extends between a respective inlet and a respective        outlet, each of the plurality of secondary conduit outlets being        disposed at the downstream end, wherein the vacuum is applied to        one of the plurality of secondary conduits and either a positive        flow or no flow of a gas is simultaneously allowed through        another of the plurality of secondary conduits.    -   the jet has a circular cross-section.    -   the lance further comprises a collar extending from the        downstream end of the main body, the collar having a wall        extending around the primary and secondary conduit outlets, an        inner surface of the wall defining a vectoring space through        which a jet of the first gas may be injected from the outlet of        the primary conduit.    -   the reaction space is a molten matte of sulfides of non-ferrous        metals.    -   the first gas is the same as the second gas and the first and        second gases are at different pressures upstream of the lance.    -   said injection of the second gas from the secondary conduit is        discontinued wherein the jet is no longer deviated towards the        co-flow.    -   said steps of applying and discontinuing are alternated such        that the jet is swept along an area described by an angle θ in        the range of 0°<θ≦45°.    -   the lance has a plurality of secondary conduits each one of        which extends between a respective inlet and a respective        outlet, each of the secondary conduit outlets being disposed at        the downstream end, wherein injection of the second gas is        alternated between the plurality of secondary conduits to        provide an alternating plurality of co-flows and to        alternatingly deviate the jet towards different ones of the        plurality of co-flows.    -   alternating injection of the second gas between two of the        secondary conduits has the effect of deviating the jet across a        total angle of greater than 0° and equal to or less than 90°.    -   the lance further comprises a collar extending from the        downstream end of the main body, the collar having a wall        extending around the primary and secondary conduit outlets, an        inner surface of the wall defining a vectoring space, wherein        the jet becomes fixed with respect to the inner surface adjacent        the secondary conduit outlet when injection of the second gas is        initated therethrough.    -   the wall has a height in the direction of the jet flow that is        1-5 times the width or diameter of the jet.    -   the lance has n secondary conduits each one of which extends        between a respective inlet and a respective outlet, each of the        secondary conduit outlets being disposed at the downstream end,        wherein injection of the second gas is alternated between the n        secondary conduits to alternatively deviate the jet between a        respective n co-flows and n is an integer in the range of from        2-6.    -   the primary conduit comprises a converging-diverging nozzle that        extends along an axis.    -   a cross-section of the collar wall inner surface taken along the        primary conduit axis has an ellipsoid configuration having first        and second ends, wherein the lance comprises an additional        secondary conduit formed in the main body that extends between a        respective inlet and a respective outlet that is disposed at the        main body downstream end, each of two secondary conduit outlets        being disposed adjacent one of the first and second ends of the        ellipsoidally configured collar wall inner surface.    -   a cross-section of the collar wall inner surface taken along the        axis has a three-lobed configuration each lobe of which        terminates in a tip, wherein the lance comprises two additional        secondary conduits each of which is formed in the main body and        extends between a respective inlet and a respective outlet that        is disposed at the downstream end, each of the three secondary        conduit outlets being disposed adjacent a respective one of the        three tips.    -   a cross-section of the collar wall inner surface taken along the        axis has a triangular configuration with three corners, wherein        the lance comprises two additional secondary conduits each of        which is formed in the main body and extends between a        respective inlet and a respective outlet disposed at the        downstream end, each of the three secondary conduit outlets        being disposed adjacent to a respective one of the three        corners.    -   the corners are rounded off.    -   a cross-section of the collar wall inner surface taken along the        axis has a four-lobed configuration each lobe of which        terminates in a tip, wherein the lance comprises three        additional secondary conduits each of which is formed in the        main body and extends between a respective inlet and a        respective outlet disposed at the downstream end, each of the        four secondary conduit outlets being disposed adjacent a        respective one of the four tips.    -   a cross-section of the collar wall inner surface taken along the        axis has a parallelogram configuration having four corners,        wherein the lance comprises three additional secondary conduits        each of which is formed in the main body and extends between a        respective inlet and a respective outlet disposed at the        downstream end, each of the four secondary conduit outlets being        disposed adjacent to a respective one of the four corners.    -   the collar wall inner surface has at least two pairs of grooves        formed therein, each groove of one of the pairs extending in a        direction parallel to the primary conduit axis from opposite        sides of a respective one of the four corners.    -   a cross-section of the secondary conduit outlet taken along the        primary conduit axis has a kidney bean configuration, wherein        the primary conduit outlet has a circular cross-section taken        along the primary conduit axis and the concave portion of the        kidney bean configuration extends coaxially with and along a        peripheral portion of the primary conduit outlet.    -   an inner surface of the wall has a circular cross-section taken        along the primary conduit axis, wherein:        -   a plurality of dividers extend inwardly from the inner wall            surface towards the primary conduit axis to define a            respective plurality of expansion zones disposed between            adjacent dividers; and        -   the lance has a plurality of the secondary conduits each one            of which extends between a respective inlet and a respective            outlet disposed at the main body downstream end, each of the            plurality of secondary conduit outlets being associated with            a respective one of the plurality of expansion zones and            disposed immediately upstream thereof.    -   the plurality of vectoring spaces consists of n expansion zones,        the plurality of secondary conduits consists of n secondary        conduits, and n is an integer in the range of from 2-6.    -   a width or diameter of the secondary conduit outlet is between        0.01 to 2.0 times a width or diameter of the primary conduit        outlet.    -   the collar has a height H extending from a plane including the        primary conduit outlet and a terminal downstream portion of the        collar, H being one to ten times the width or diameter of the        primary conduit.    -   the collar inner wall surface diverges in straight-line fashion        away from the primary conduit outlet.    -   the collar inner wall surface diverges in curved-line fashion        away from the primary conduit outlet.

BRIEF DESCRIPTION OF THE DRAWINGS

For a further understanding of the nature and objects of the presentinvention, reference should be made to the following detaileddescription, taken in conjunction with the accompanying drawings, inwhich like elements are given the same or analogous reference numbersand wherein:

FIG. 1A is a schematic cross-sectional view of a counterflow embodimentof the invention.

FIG. 1B is a schematic cross-sectional view of a co-flow embodiment ofthe invention.

FIG. 1C is a schematic cross-section of a collar having an inner wallsurface that diverges concavely away from the axis of the jet.

FIG. 1D is a schematic cross-section of a collar having an inner wallsurface that diverges in a straight line away from the axis of the jet.

FIG. 2A is a isometric view of a lance whose jet may be deviated betweenopposite sides of an ellipsoid collar wall.

FIG. 2B is a top view of the lance of FIG. 2A.

FIG. 2C is an expanded section of the top view of FIG. 2A.

FIG. 3 is a cross-sectional view of the lance of FIGS. 1, 2A, and 2Btaken along line A-A.

FIG. 4 is a cross-sectional view of the lance of FIGS. 1, 2A, 2B, and 3taken along line B-B.

FIG. 5A is a top view of a lance whose jet may be deviated betweendifferent lobes of a tri-lobed collar wall.

FIG. 5B is an expanded section of the top view of FIG. 5A.

FIG. 6 is a isometric view of the lance of FIG. 5.

FIG. 7 is a top view of a lance whose jet may be deviated betweendifferent corners of a triangular collar wall.

FIG. 8 is a isometric view of the lance of FIG. 7.

FIG. 9 is a top view of the lance of FIG. 7 with the top collar 39Bremoved.

FIG. 10 is a isometric view of a lance whose jet may be deviated betweendifferent corners of a square collar wherein each of one pair of opposedcorners is associated with a collar wall groove.

FIG. 11 is the isometric view of FIG. 10 with portions broken away.

FIG. 12A is an exploded, isometric view of the lance of FIGS. 10 and 11wherein all corners are associated with collar wall grooves.

FIG. 12B is an expanded section of the exploded, isometric view of FIG.12A.

FIG. 13A is a top view of the lance of FIGS. 10, 11, 12A, and 12B.

FIG. 13B is an expanded section of the top view of FIG. 13A.

FIG. 14A is a side elevation view of the lance of FIGS. 10, 11, 12A-12B,and 13A-13B.

FIG. 14B is a cross-sectional view of the lance of FIG. 14A taken alongline B-B.

FIG. 14C is a cross-sectional view of the lance of FIG. 14A taken alongline C-C.

FIG. 14D is a cross-sectional view of the lance of FIG. 14A taken alongline D-D.

FIG. 14E is a cross-sectional view of the lance of FIG. 14A taken alongline E-E.

FIG. 15 is a cross-sectional view of the lance of FIGS. 10, 11, 12A-12B,13A-13B, and 14A-14E taken along line A-A.

FIG. 16 is a isometric view of a lance whose jet may be deviated betweendifferent quarters of a circular collar wall that are separated bydividers.

FIG. 17 is a top view of the lance of FIG. 15.

FIG. 18 is a cross-sectional view of the lance of FIGS. 15 and 16 takenalong line A-A.

FIG. 19 is a schematic top view of an application of the lance in whichthe jet is horizontally swept.

FIG. 20 is a schematic side view of an application of the lance in whichthe jet is vertically swept.

FIG. 21 is an isometric view of a lance with an extended collar with onesegment removed.

FIG. 22 is an isometric view of the lance of FIG. 21 with two segmentsremoved.

FIG. 23 is a top view of the lance of FIGS. 21-22.

FIG. 24 is a cross-sectional view of the lance of FIGS. 21-23 takenalong line A-A.

DESCRIPTION OF PREFERRED EMBODIMENTS

The invention is directed to a lance, lancing systems, and methods forinjecting a gaseous substance into a reaction space wherein fluidictechniques are utilized to deviate a jet of gaseous substance in adesired direction.

A lance used according to the method includes a main body havingupstream and downstream ends and a primary conduit formed therein and atleast one secondary conduit formed therein. Each of the primary andsecondary conduits extend between an associated inlet and an associatedoutlet each of which is disposed at the downstream end of the main body.The primary conduit inlet is adapted to be placed in fluid communicationwith a source of a first gas. The secondary conduit inlet is adapted tobe placed in fluid communication with either a source of vacuum or asource of a second gas. The lance may optionally include a collar. Thecollar includes a wall extending around the primary and secondaryconduit outlets from the main body downstream end. An inner surface ofthe wall defines a vectoring space adapted to allow a jet of the firstgas exiting the primary conduit outlet to flow therethrough. The sourceof the first gas may be the same as or different from the source of thesecond gas. The secondary conduit outlet is disposed at a locationadjacent the primary conduit outlet sufficient to fluidically deviate ajet of the first gas exiting the primary conduit outlet towards thecollar inner wall surface adjacent the secondary conduit outlet when thesecondary conduit inlet is placed in fluid communication with either thevacuum source or the source of the second gas.

A counter-flow embodiment of a method according to the inventionincludes the following steps. A jet of the first gas is injected fromthe outlet of the primary conduit and into the reaction space. A vacuumis applied to the secondary conduit to create a counterflow of a gasinto the secondary conduit outlet from the reaction space interior andthe jet is deviated towards the counterflow. Without being bound by anyparticular theory, we believe that a difference in static pressurebetween the jet and the counterflow at the outlets causes deviation ofthe jet towards the co-flow of second gas.

A co-flow embodiment of a method according to the invention includes thefollowing steps. A jet of the first gas is injected from the outlet ofthe primary conduit and into the reaction space. A second gas isinjected from the outlet of the secondary conduit to create a co-flow ofthe second gas parallel to an axis of the jet and adjacent a peripheralregion of the jet. The jet is deviated towards the co-flow of secondgas.

In the co-flow embodiment, the co-flow itself is overexpanded. The firstand second gases may be the same or different. The axis along which thesecondary conduit is oriented may be parallel or at an angle to an axisalong which the primary conduit is oriented. In the latter case, the twoaxes diverge as they proceed from an upstream direction to a downstreamdirection. In this manner, the secondary conduit is not oriented towardsthe primary conduit so as to cause direct impingement of the co-flowupon the jet and momentum transfer.

The jet angle may be controlled by using a secondary flow (co-flow orcounterflow) that is adjacent to the jet whereby the ratio of the staticpressure of the secondary flow to that of the jet at the outlets is lessthan 1. Without being bound by any particular theory, we believe that,due to the difference in static pressures between the jet and thesecondary flow, the jet is deviated or “bent” towards the secondaryflow. For ideally expanded jets, this means that the static pressure ofthe secondary flow is sub atmospheric. The ratio may be achieved in twodifferent ways: with a secondary flow that flows in a direction oppositethat of the jet (counterflow) or with a secondary flow that flows in thesame direction as that of the jet (co-flow). Regardless of whether thecounterflow or co-flow alternatives are used, use of this techniqueallows continuous deviating or bending (i.e., vectoring) of the jet fromzero to a maximum deviation angle.

A description of the theorized mechanism now follows with reference totwo non-limiting examples.

A counterflow embodiment of this vectoring is illustrated in FIG. 1A. Amain flow MF of a first gas flows through a primary conduit that extendsthrough a main body of a lance and whose terminal portion includesnozzle N₁. The main flow MF exits the nozzle N₁ along an axis X andemerges as a jet J. A secondary conduit also extends through the lancein between the nozzle N₁ and the collar C₁. If a vacuum is applied toproduce a first counterflow CF₁ in the secondary conduit, the jet J isvectored/deviated by an angle α₁ away from the axis X and towards oneside of the collar C₁. The lance includes another secondary conduit alsoextending between the nozzle N₁ and the collar C₁ on a side of the jet Jopposite that of the first counterflow F₁. If the vacuum is insteadapplied to produce a second counterflow CF₂ in this other secondaryconduit, the jet J is vectored/deviated by an angle α₂ away from theaxis X and towards the opposite side of the collar C₁. Thus, if thevacuum is alternatingly applied to opposite areas adjacent the jet J toproduce alternation between counterflow F₁ and counterflow F₂, the totalangle by which the jet J is deviated by the alternating counterflows F₁,F₂ is the sum of the individual angles α₁+α₂ and the jet J is sweptacross a target area generally described by a straight line.

In the counterflow embodiment, the vacuum may be supplied by an externalvacuum pump fluidly communicating with the secondary conduit throughwhich the counterflow is desired. Alternatively, the vacuum may besupplied with an external ejector pump using compressed gas. One ofordinary skill in the art will recognize that such an ejector pumpdirects compressed gas (such as air) through a converging-divergingnozzle. An opening in the nozzle is disposed in the diverging portion ofthe ejector pump adjacent the nozzle's neck. This opening fluidlycommunicates with the secondary conduit in the lance. The vacuum mayinstead be supplied by another lance in which case the primary conduitin the other lance is a converging-diverging nozzle. In this manner, alance utilizing counterflow is supplied with vacuum from another lanceassociated with the reaction space and which is operated withoutcounterflow. This other lance may be identical to the lance of FIG. 1Aand operable according to the invention or it may be different.

A co-flow embodiment of this vectoring is illustrated in FIG. 1B. A mainflow MF of the first gas flows through a primary conduit that extendsthrough a main body of a lance and whose terminal portion includesnozzle N₂. The main flow MF exits the nozzle N₂ along an axis X andemerges as a jet J. The lance also includes two secondary conduits eachone of which extends through a different portion of the lance betweenthe nozzle N₂ and the collar C₂. A co-flow CF₃ of a second gas (whichmay the same as or different from the first gas) emerges from one of thesecondary conduits. One of ordinary skill in the art will recognize thatthe static pressure of the co-flow CF₃ and of the jet J is a function ofthe upstream pressure of the supply of the gases for the co-flow CF₃ andthe jet J and also of the geometrical configuration of the nozzle N₂ andcollar C₂. Thus, the pressures of the gases upstream of the nozzle N₂for each of the jet J and co-flow CF₃ and the configuration of thenozzle N₂ are selected such that the static pressure of the co-flow CF₃adjacent the jet J is lower than of the main jet J. Based upon a givennozzle configuration, if insufficient deviation of the jet J isobserved, an operator simply may increase the upstream pressure of thesecond gas for co-flow CF₃ in an empirical manner until a sufficientdeviation by an angle α₃ away from the axis X and towards the co-flowCF₃ is observed. If deviation of the jet J in the opposite direction isdesired, co-flow CF₃ is discontinued and a co-flow CF₄ of the second gasis initiated through the other of the secondary conduits on an oppositeside of the jet J. The pressures of the gases upstream of the nozzle N₂for each of the jet J and co-flow CF₄ and the configuration of thenozzle N₂ are selected such that the static pressure of the co-flow CF₄adjacent the main jet J is lower than of the jet J. Again, based upon agiven nozzle configuration, if insufficient deviation of the jet J isobserved, an operator may simply increase the upstream pressure of thegaseous substance for co-flow CF₄ in an empirical manner until asufficient deviation by an angle α₄ is observed. Thus, if the co-flowsCF₃ and CF₄ are alternated, the total angle by which the jet J isdeviated by the alternating co-flows F₃, F₄ is the sum of the individualangles α₃+α₄ and the jet J is swept across a target area generallydescribed by a straight line.

It is believed that each single deviation angle may reach as high as45°. For reaction spaces that are enclosed by a structure (such asfurnace refractory), angles beyond 45° may cause the jet to reach tooclose to the enclosed structure may cause significant damage thereto.

While each of FIGS. 1A and 1B illustrate specific configurations, suchconfigurations are not essential to the invention. Rather, the lanceneed only have a primary conduit through which the first gas flows and asecondary conduit through which flows either the counterflow or theco-flow. While a collar is not essential to the invention, use of acollar brings some benefits. In the counterflow embodiment, the collarserves as a surface against which the jet may attach by the Coandaeffect. Thus, the deviation of the jet is rendered more accurate andrepeatable. Also, the collar serves to lower the degree of vacuumrequired in comparison to when no collar is used. When no collar isused, a relatively higher degree of vacuum is needed because not only isthe jet drawn towards the area of lower static pressure associated withthe counterflow, furnaces gases on other sides of the jet tend to bedrawn towards the low static pressure area as well. Thus, part of thevacuum is “consumed” by such drawing in. In contrast, when a collar isused, no or less of such drawing in of furnace gases occurs. In theco-flow mode, the collar serves to establish a more pronounceddifferential static pressure between the co-flow and the jet. When theco-flow is not bounded on one side by a collar, the co-flow entrainssurrounding furnace gases that tend to decrease the velocity of theco-flow and diffuse the static pressure. When the co-flow is bounded bythe collar, little of such entrainment occurs, so the velocity is mucheasier to maintain. In other words, a higher upstream pressure is neededfor the co-flow to achieve a given velocity and static pressure when nocollar is used in comparison to when a collar is used.

The utilization of moving parts at location can render those partssusceptible to corrosion or thermal damage from the heat or gases fromthe reaction space. Nevertheless, the collar may be of rotating type.This means that the collar may have an outer plate having one or moreopenings for the counterflow or co-flow that is rotatable with respectto the rest of the lance. In this manner, rotation of the outer platemay allow a counterflow or co-flow adjacent one region of the jet whiledisallowing such a counterflow or co-flow at another region of the jet.Further rotation of the outer plate may disallow the first counterflowor co-flow while allowing the second counterflow or co-flow.

The collar is a structure that extends from a main body of the lanceadjacent the primary and secondary conduit outlets to a downstreamextremity of the lance. The collar includes a wall that extends aroundthe outlets of the primary conduit (from which the jet emanates) and theoutlet(s) of the secondary conduit(s). The inner surface of the walldefines a vectoring space and provides a surface upon which the jet mayattach given sufficient deviation by the fluidic means of thecounterflow or co-flow. While the wall may partially surround theoutlets, it is believed that better performance is realized when thewall completely surrounds the outlets.

In the co-flow embodiment, one of ordinary skill in the art willrecognize that the jet will not attach per se, but instead becomes fixedwith respect to the surface. Thus, throughout the Specification the word“attach” is used to denote that that the jet becomes fixed with respectto the surface whether or not it actually touches the surface. Thisapplies to both the co-flow and counterflow embodiments.

The inner wall surface may be configured in a variety of shapes. Forexample, a cross-sectional shape of the inner wall surface may be acircle, ellipse, square, triangle, tri-lobed, four-lobed, five-lobed,six-lobed, a pentagon, or a hexagon. Regular polygons with more than sixsides are also included within the scope of the invention but aresomewhat less preferred because of the relatively greater difficulty inattaching the jet to a particular side. The inner wall surface may alsoinclude dividers that extend inwardly towards the jet. These dividersserve the purpose of partially dividing the space enclosed by the innerwall surface into a plurality of vectoring sub-spaces. Each of theplurality of vectoring sub-spaces is associated with a respectivesecondary conduit outlet allowing a respective counterflows or co-flowtherethrough. The dividers should not be overly long such that theirinnermost edges interfere with the jet. Instead of dividers, theplurality of vectoring sub-spaces may be separated by a plurality of gascurtains.

In the case where no dividers are used with the collar, the vectoringspace may still be divided into a plurality of vectoring sub-spaces.This may be accomplished by selecting a collar wall inner surfaceconfiguration whose cross-section along the axis of the primary conduitis different from that of the primary conduit outlet. For example, ifthe primary conduit outlet has a circular cross-sectional shape, whilethe collar wall inner surface could have an ellipsoid, square,triangular, tri-lobed, four-lobed, five-lobed, six-lobed, pentagonal, orhexagonal cross-sectional shape. The primary conduit outlet and collarwall inner surface configurations and relative sizes are selected suchthat the peripheral regions of the jet touch the collar inner wallsurface at a plurality of tangency points. In a first particularexample, a properly sized primary conduit outlet and triangular collarwall inner surface will yield a centrally disposed circular areaaccommodating the jet as well as three vectoring sub-spaces. In thisparticular example, each of the vectoring sub-spaces is defined by aportion of one of the corners of the triangle and an arc that extendsalong a partial circumference of the jet. In a second particularexample, the primary conduit outlet could have a square cross-sectionalshape and the collar inner wall surface could have a circularcross-section. A properly sized primary conduit and a properly sizedcollar inner wall will yield a centrally disposed square areaaccommodating the jet as well as four circular segments. Each of thecircular segments would have an outer boundary consisting of an arc andan inner boundary consisting of a chord that extends along one of thesides of the jet. Several others of these combinations of primaryconduit outlet and collar inner wall surface configurations arepossible, including but not limited to:

-   -   a circular primary conduit outlet and a square, pentagonal,        hexagonal, tri-lobed, or four-lobed collar wall inner surface;    -   a circular collar wall inner surface and a triangular, square,        pentagonal, hexagonal, tri-lobed or four-lobed primary conduit        outlet.        For ease of machining, the first group of combinations is        preferred.

The collar inner wall surface can extend parallel to the axis of theprimary conduit. Alternatively, the collar wall inner surface can andpreferably does diverge outwardly away from the primary conduit axis. Insuch a case, the divergence may take any of several configurations, twoof which will now be described

As best illustrated by FIG. 1C, a collar C₃ has a wall portion with aheight H₃ that extends downstream from an outlet of the primary conduitN₃ from which the jet J₃ originates. The height of the inner collar wallis typically between about one to five times the width or diameter D₃ ofthe nozzle N₃ or jet J₃. A gap G₃ between the nozzle N₃ and the collarC₃ at the outlet of the nozzle N₃ (representing the width or diameter ofthe counterflow or co-flow) is typically anywhere between 0.01 to 2.0times the width/diameter D₃ of the nozzle N₃ or jet J₃. The inner wallsurface IW₃ smoothly diverges concavely away from an axis X₃ of thenozzle N₃ (which also corresponds to an axis of the jet J₃ when it isnot deviated according to the invention).

As best illustrated by FIG. 1D, a collar C₄ has a wall portion with aheight H₄ that extends downstream from an outlet of the primary conduitN₃ from which the jet J₄ originates. The height of the inner collar wallis typically between about one to five times the width or diameter D₄ ofthe nozzle N₄ or jet J₄. A gap G₄ between the nozzle N₄ and the collarC₄ at the outlet of the nozzle N₄ (representing the width or diameter ofthe counterflow or co-flow) is typically anywhere between 0.01 to 2.0times the width/diameter D₄ of nozzle N₄ or jet J₄. The inner wallsurface IW₄ diverges in a straight line away from an axis X₄ of thenozzle N₄ (which also corresponds to an axis of the jet J₄ when it isnot deviated according to the invention).

The invention may be practiced with the collars of FIGS. 1C and 1D ineither the co-flow or the counterflow embodiments.

Regardless of whether co-flow or counterflow is utilized, the collar ofcourse provides a maximum limit to which the jet may be deviated. Underconditions where the jet has not been deviated sufficiently to attach itto the collar, increasing the static pressure ratio between the jet andthe co-flow or counterflow will further deviate the jet until itattaches. Once it attaches, further increases in the static pressureratio between the jet and the co-flow or counterflow will have nofurther effect upon the jet deviation angle so long as the nozzle, Machnumber and flow rates remain constant. However, the maximum deviationangle can be varied by modifying the nozzle design, and when a collar isutilized, the collar design. Under conditions where the jet has notalready reached its maximum deviation limit due to the nozzle or collardesign, the maximum deviation angle can also be varied by changing theMach number or by changing the flow rate of the primary jet (byincreasing its upstream pressure), or in the case of the counterflowembodiment the level of vacuum may be increased.

Depending upon where one desires to inject the first gas with the lance,many different lancing patterns and corresponding lance configurationsmay be imagined. If several different openings are provided in the lanceadjacent the primary conduit for the jet, several different counterflowsor co-flows are possible. While the jet is typically deviated throughthe fluidic action of only one counterflow or co-flow, the combinedaction or two or more counterflows and/or co-flows at differentperipheral regions of the jet may instead be used. Indeed, a counterflowmay be applied to the desired region of deviation while no flow or apositive flow (at relatively low pressures/flow rates) of the first gasmay be allowed at other regions. In another configuration, a co-flow maybe applied to the desired region of deviation while other openings arekept open. Similarly other openings could be blocked for preventing anyflow therethrough.

The invention also allows dynamic control of the lance. In thecounterflow mode, varying the degree of vacuum applied to create thecounterflow can result in deviation of the jet to any angle in betweenzero and the maximum angle without requiring reconfiguration of thelance. Additionally, alternation between two different counterflows orco-flows on different sides of the jet will result in alternatingvectoring of the jet in different directions. Thus, the jet may be sweptacross a desired target area instead of being directed towards only onespot. Because this is done fluidically, there is no need for movingparts susceptible to corrosion from the high temperature of and/or gasesfrom the furnace. Rather, alternation between the two counterflows orco-flows may be achieved by remotely alternating application of a vacuumor high pressure second gas to different conduits that are in fluidcommunication with the secondary conduit outlets. In one aspect of theinvention, the vectoring of the jet may follow a pattern in which casethe alternation between the various counterflows or co-flows may becontrolled with a programmable logic controller.

Typically, the jet is typically vectored in anywhere between 1 to 6different directions. In other words, the jet is typically deviated fromthe axis extending from the primary conduit outlet towards 1 to 6different directions. However, a greater number of vectoring directionsis possible with the caveat that relatively less accurate deviations ofthe jet are believed to occur with such high numbers of vectoringdirections. In the case of a square or rectangular jet, it may bevectored in 1 to 4 directions: top, bottom, left, and right. A circularjet may be vectored in any number of directions depending upon theplacement and number of secondary conduit outlets. The jet may be sweptin any number of different ways: horizontally, vertically, diagonally,etc. The jet may be swept in a repeated pattern or be swept in anirregular manner. Such repeated or irregular sweeping may be controlledwith the use of a programmable logic controller written with analgorithm adapted to control application of the counterflow or co-flowto the appropriate secondary conduit for accomplishing the desired sweepconditions.

The jet may be of any gas (the first gas) desired for injection into areaction space including, but are not limited to, oxygen,oxygen-enriched air, natural gas and inert gases such as nitrogen orargon. In the case of oxygen, it typically has a purity of from 90-100%.In the co-flow embodiment, the second gas may be the same as the firstgas or different. Typically, the second gas is the same as the firstgas, but at a higher pressure. Also, the co-flow can be at ambienttemperature (also called “cold”) or preheated. Preheating decreases themixing rate between the jet and the co-flow.

The velocity of the jet may be supersonic or subsonic, typically in therange of from about 0.3 Mach to about 5.0 Mach. The flow rate of the jetis typically anywhere between about 200 Nm³/h to about 4000 Nm³/h whilethe co-flow is typically about 50 Nm3/h to about 1200 Nm³/h. The widthor diameter of the co-flow is typically 0.01 to about 2.0 times thewidth or diameter of jet. When the invention is applied to metalrefining applications in larger vessels (such as a basic oxygenfurnace), the flow rate can be much higher (for example 10,000 Nm³/h).In the case of supersonic jets, they can be ideally expanded orunder-expanded.

Types of reaction spaces receiving the injected first gas include, butare not limited to, EAFs, BOFs, QBOP, AODs, VODs, and non-ferrousfoundries. The reactant in the reaction space is a liquid or a solid andincludes, but is not limited to, steel, metal parts, and non-ferrousmetals.

Lances

Many different types of lances are included within the scope of theinvention. The primary conduit outlet may have a square, rectangular,elliptical, circular, triangular, pentagonal, or hexagonalcross-section. For ease of manufacture, the primary conduit and primaryconduit outlet preferably have a circular or square cross-section. Thelance also includes at least one secondary conduit (typically one to sixbut sometimes more. While the cross-section of the secondary conduitoutlet may have any configuration, in the counterflow mode the secondaryconduit outlet is preferably kidney bean shaped when the primary conduitoutlet is circular. In such a case, the concave portion of the kidneybean shape extends along a peripheral region of the primary conduitoutlet. This arrangement is believed to achieve the lowest pressure dropacross the vacuum conduit in comparison to secondary conduit outlets ofdifferent configurations. The lance can have water cooling jacketsaround it in order to protect them from relatively high temperaturesthat may be encountered in a reaction space comprising a furnace.

While the lance used according to the invention may have a wide varietyof configurations, descriptions of typical examples now follow.

As best illustrated in FIGS. 2A, 2B, 2C, 3, and 4, one lance embodimentincludes a collar 9 secured to a main body 7 with fasteners insertedthrough bores 11. A converging-diverging primary conduit is formed in amain body 7. The primary conduit extends between an inlet 1 and outlet12 and includes a straight section 2, a converging section 4 whichnarrows to a neck 6, and a diverging section 8 which extends along anaxis. Two secondary conduits are formed in the collar 9. The firstsecondary conduit extends between an inlet 3A and an outlet 14A, whilethe second secondary conduit extends between an inlet 3B and an outlet14B. While FIGS. 2A, 2B, 2C, 3, and 4 illustrate secondary conduitshaving a stepped and somewhat axially asymmetric shape, the secondaryconduits may be configured more symmetrically and may extend parallelthe primary conduit. This latter alternative is more typically opted forwhen the co-flow embodiment is being practiced. The collar 9 includes awall that circumferentially extends from and around the primary conduitoutlet 12 and secondary conduit outlets 14A, 14B and extends in adownstream direction to terminate in a beveled surface B. The innersurface of the collar wall has an ellipsoid cross-sectional shape. Themiddle portion of the inner wall surface extends in a direction parallelto an axis of the primary conduit. Adjacent each secondary conduitoutlet 14A, 14B are corresponding inner wall surface end portions 5A,5B. The end portions 5A, 5B diverge outwardly at an oblique angle to theprimary conduit axis. Before the fluidic deviation according to theinvention is initiated, a jet gas (which for clarity's sake will betermed the first gas) exits the primary conduit outlet 12 along the axisof the primary conduit. The inner wall surface defines a vectoring spaceinto which the jet can expand. For ease of manufacture, the collar 9 andmain body 7 are typically machined separately and are fastened togetheras described above. However, they may be formed in a single integralpiece and later machined to form all of the necessary structures.

In the counterflow embodiment of the lance of FIGS. 2A, 2B, 2C, 3, and4, a vacuum is supplied to the inlet 3A of one of the secondaryconduits. This creates a region of sub atmospheric pressure adjacent aperipheral region of the jet in the vectoring space downstream of outlet14A. Due to the pressure differential between the region of subatmospheric pressure and the jet, the jet is deviated at an angle to theaxis of the primary conduit towards inner wall surface 5A. Given asufficient degree of applied vacuum, the jet will “attach” to the innerwall surface 5A to produce a stable deviated jet. At the same time,inlet 3B can be open or closed or a coflow of the second gas can also besupplied through it. Similarly, application of vacuum to inlet 3B of theother of the secondary conduits will deviate the jet towards inner wallsurface 5B and attach given a sufficient degree of vacuum. For a givenflow rate of the first gas through a given lance, the degree of vacuummay be adjusted in an empirical manner to determine and optimal level.

In the co-flow embodiment of the lance of FIGS. 2A, 2B, 2C, 3, and 4, aflow of gas (which for clarity's sake will be termed the second gas butwhich may have the same or different composition as the first gas) isallowed through a secondary conduit and exits outlet 14A. The pressuresof the sources of first and second gases upstream of the primary andsecondary conduits are selected such that the static pressure of theco-flow adjacent the jet is lower than of the jet. This creates apressure differential between the co-flow and the jet which deviates thejet towards the end portion 5A. Given a sufficiently great pressuredifferential, the jet “attaches” to the end portion 5A of the inner wallsurface to produce a stable deviated jet. Similarly, if the flow of thesecond gas is instead initiated through the other secondary conduit andexits outlet 14B, the jet is deviated towards the end portion 5B andattach given a sufficiently high pressure differential. One of ordinaryskill in the art will recognize that a sufficiently higher velocity ofthe co-flowing second gas adjacent the jet will create the pressuredifferential necessary for deviation of the jet. Because the flow rateof the first gas is driven by the requirements of the reaction space andis typically fixed, for a given lance configuration, an operator mayadjust the pressure of the second gas upstream of the secondary conduitin an empirical manner in order to achieve a desired velocity for theco-flow and thus a desired pressure differential.

Regardless of whether the lance of FIGS. 2A, 2B, 2C, 3, and 4 isoperated according to the counterflow or the co-flow embodiment,alternation of vacuum applied to, or flow of the second gas allowedthrough, the two secondary conduits will alternatingly deviate the jetback and forth across a generally straight line-shaped target area.

As best illustrated in FIGS. 5A, 5B, and 6, another lance embodimentincludes a collar 29 secured to a main body 7 with fasteners insertedthrough bores 11. A converging-diverging primary conduit is formed inthe main body 7 and extends along an axis. The primary conduit extendsbetween an inlet and outlet 12. Three secondary conduits are formed inthe collar 29. The first secondary conduit extends between an inlet 3Aand an outlet 24A, while the second and third secondary conduitscorrespondingly extend between inlets 3B, 3C and outlets 24B, 24C. Thecollar 29 includes a wall that circumferentially extends from and aroundthe primary conduit outlet 12 and secondary conduit outlets 24A, 24B,24C and extends in a downstream direction to terminate in a beveledsurface B2. The inner surface of the collar wall has a three-lobedcross-sectional shape. Each of the secondary conduit outlets 24A, 24B,24C is disposed adjacent to and immediately upstream of a respectivecollar wall inner surface lobe portion 25A, 25B, 25C. The collar wallinner surface also includes inwardly extending partial dividers 25G,25E, 25F that separate adjacently disposed lobe portions 25A and 25B,25B and 25C, and 25C and 25A, respectively. The collar wall innersurface extends in a direction parallel to the axis of the primaryconduit at each of the dividers 25G, 25E, 25F but diverges outwardlyaway from the primary conduit outlet 12 at the lobe portions 25A, 25B,25C. Before the fluidic deviation according to the invention isinitiated, the first gas exits the primary conduit outlet 12 as a jetalong the axis of the primary conduit. The inner collar wall surfacedefines a vectoring space into which the jet can expand. For ease ofmanufacture, the collar 29 and main body 7 are typically machinedseparately and are fastened together as described above. However, theymay be formed in a single integral piece and later machined to form allof the necessary structures.

In the counterflow embodiment the lance of FIGS. 5A, 5B, and 6, a vacuumis supplied to the inlet 3A of one of the three secondary conduits. Thiscreates a region of sub atmospheric pressure adjacent a peripheralregion of the jet in the vectoring space downstream of outlet 24A. Dueto the pressure differential between the region of sub atmosphericpressure and the jet, the jet is deviated at an angle to the axis of theprimary conduit towards lobe portion 25A. Given a sufficient degree ofapplied vacuum, the jet will “attach” to the lobe portion 25A to producea stable deviated jet. Similarly, application of vacuum to an inlet 3B,3C of one of the other secondary conduits will deviate the jet towardslobe portion 25B, 25C, respectively and attach given a sufficient degreeof vacuum. For a given flow rate of the first gas through a given lance,the degree of vacuum may be adjusted in an empirical manner to determineand optimal level.

In the co-flow embodiment the lance of FIGS. 5A, 5B, and 6, a flow ofthe second gas is allowed through a secondary conduit and exits outlet24A. The pressures of the sources of first and second gases upstream ofthe primary and secondary conduits are selected such that the staticpressure of the co-flow adjacent the jet is lower than of the jet. Thiscreates a pressure differential between the co-flow and the jet whichdeviates the jet towards the lobe portion 25A. Given a sufficientlygreat pressure differential, the jet “attaches” to the lobe portion 25Ato produce a stable deviated jet. Similarly, if the flow of the secondgas is instead initiated through another of the secondary conduit andexits outlet 24B or 24C, the jet is deviated towards a respective lobeportion 25B, 25C and attaches given a sufficiently high pressuredifferential. One of ordinary skill in the art will recognize that asufficiently higher velocity of the co-flowing second gas adjacent thejet will create the pressure differential necessary for deviation of thejet. Because the flow rate of the first gas is driven by therequirements of the reaction space and is typically fixed, for a givenlance configuration, an operator may adjust the pressure of the secondgas upstream of the secondary conduit in an empirical manner in order toachieve a desired velocity for the co-flow and thus a desired pressuredifferential.

Regardless of whether the lance of FIGS. 5A, 5B, and 6 is operatedaccording to the counterflow or the co-flow embodiment, alternation ofvacuum applied to, or flow of the second gas allowed through, the threesecondary conduits will alternatingly deviate the jet back and forthacross a generally triangular target area.

As best illustrated in FIGS. 7, 8, and 9, another lance embodimentincludes an intermediate collar 39A secured to a main body 7 withfasteners inserted through bores 11 and a top collar 39B secured to theintermediate collar 39A with fasteners inserted through bores S3. Aconverging-diverging primary conduit is formed in the main body 7 andextends along an axis. The primary conduit extends between an inlet andoutlet 12. Three secondary conduits are formed in the intermediatecollar 39A. The first secondary conduit extends between an inlet 3A andan outlet 34A, while the second and third secondary conduitscorrespondingly extend between inlets 3B, 3C and outlets 34B, 34C. Thetop collar 39A includes a wall that circumferentially extends from andaround the primary conduit outlet 12 and secondary conduit outlets 34A,34B, 34C and extends in a downstream direction to terminate in a beveledsurface B3. The inner surface of the top collar wall has a triangularcross-sectional shape with rounded corners. Each of the secondaryconduit outlets 34A, 34B, 34C is disposed adjacent to and immediatelyupstream of a respective corner 35A, 35B, 35C of the inner wall surfaceof the top collar 39B. Except for the corners 35A, 35B, 35C, the innerwall surface of the top collar 39B extends in a direction parallel tothe axis of the primary conduit. At the corners 35A, 35B, 35C, the innerwall surface of the top collar 39B diverges outwardly away from theprimary conduit outlet 12. Before the fluidic deviation according to theinvention is initiated, the first gas exits the primary conduit outlet12 as a jet along the axis of the primary conduit. The inner wallsurface of the top collar 39B defines a vectoring space into which thejet can expand. For ease of manufacture, the intermediate collar 39A,top collar 39B, and main body 7 are typically machined separately andare fastened together as described above. However, they may be formed ina single integral piece and later machined to form all of the necessarystructures.

In the counterflow embodiment for the lance of FIGS. 7, 8, and 9, avacuum is supplied to the inlet 3A of one of the three secondaryconduits. This creates a region of sub atmospheric pressure adjacent aperipheral region of the jet in the vectoring space downstream of outlet34A. Due to the pressure differential between the region of subatmospheric pressure and the jet, the jet is deviated at an angle to theaxis of the primary conduit towards corner 35A. Given a sufficientdegree of applied vacuum, the jet will “attach” to the corner 35A toproduce a stable deviated jet. Similarly, application of vacuum to aninlet 3B, 3C of one of the other secondary conduits will deviate the jettowards corner 35B, 35C, respectively and attach given a sufficientdegree of vacuum. For a given flow rate of the first gas through a givenlance, the degree of vacuum may be adjusted in an empirical manner todetermine and optimal level.

In the co-flow embodiment for the lance of FIGS. 7, 8, and 9, a flow ofthe second gas is allowed through a secondary conduit and exits outlet34A. The pressures of the sources of first and second gases upstream ofthe primary and secondary conduits are selected such that the staticpressure of the co-flow adjacent the jet is lower than of the jet. Thiscreates a pressure differential between the co-flow and the jet whichdeviates the jet towards the lobe portion 35A. Given a sufficientlygreat pressure differential, the jet “attaches” to corner 35A to producea stable deviated jet. Similarly, if the flow of the second gas isinstead initiated through another of the secondary conduit and exitsoutlet 34B or 34C, the jet is deviated towards a respective corner 35B,35C and attaches given a sufficiently high pressure differential. One ofordinary skill in the art will recognize that a sufficiently highervelocity of the co-flowing second gas adjacent the jet will create thepressure differential necessary for deviation of the jet. Because theflow rate of the first gas is driven by the requirements of the reactionspace and is typically fixed, for a given lance configuration, anoperator may adjust the pressure of the second gas upstream of thesecondary conduit in an empirical manner in order to achieve a desiredvelocity for the co-flow and thus a desired pressure differential.

Regardless of whether the lance of FIGS. 7, 8, and 9 is operatedaccording to the counterflow or the co-flow embodiment, alternation ofvacuum applied to, or flow of the second gas allowed through, the threesecondary conduits will alternatingly deviate the jet back and forthacross a generally triangular target area.

As best illustrated in FIGS. 10, 11, 12A-12B, 13A-13B, 14A-14D, and 15,another lance embodiment includes an intermediate collar 49A secured toa main body 7 with fasteners inserted through bores 11 and a top collar49B secured to the intermediate collar 49A with fasteners insertedthrough bores S4. A converging-diverging primary conduit is formed inthe main body 7 and extends along an axis between an inlet and outlet12. It includes a straight section 2, a converging section which narrowsto a neck 6 and a diverging section. Four secondary conduits are formedin the intermediate collar 49A. The first secondary conduit extendsbetween an inlet 3A and an outlet 44A, while the second, third, andfourth secondary conduits correspondingly extend between inlets 3B, 3C,3D and outlets 44B, 44C, 44D, respectively. The top collar 49A includesa wall that circumferentially extends from and around the primaryconduit outlet 12 and secondary conduit outlets 44A, 44B, 44C, 44D. Eachof the secondary conduit outlets 44A, 44B, 44C, 44D is disposed adjacentto and upstream of a respective corner 45A, 45B, 45C, 45D of the innerwall surface of the top collar 39B.

The inner surface of the top collar wall has a generally frustopyramidal(frustum of a pyramid) shape with four corners 45A, 45B, 45C, 45D andgrooves G formed in two corners 45A, 45C. Before the fluidic deviationaccording to the invention is initiated, the first gas exits the primaryconduit outlet 12 as a jet along the axis of the primary conduit and thegrooved, frustopyramidal top collar inner wall surface defines avectoring space into which the jet can expand. Each groove G representsthe portion of the associated corner 45A, 45C that is machined away inorder to project the cross-sectional shape of the secondary conduitoutlets 44A, 44C in the downstream direction parallel to the primaryconduit axis. The frustopyramidal aspect of the top collar inner wallsurface includes a small base adjacent the primary and secondary conduitoutlets 12, 44A, 44B, 44C, 44D and a large base at the downstreamextremity of top collar 49B.

As best illustrated in FIG. 14B, the narrow base has a pair of oppositecorners 45B, 45D. At the other opposite portions of the narrow base arecurved surfaces 145A, 145C. In between curved surface 145A and corner45B is a jutting portion 145A′ while jutting portion 145A″ is in betweencurved surface 145A and corner 45D. Jutting portions 145C′, 145C″ are inbetween curved surface 145C & corner 45B and curved surface 145C andcorner 45D, respectively. As best shown in FIGS. 14C-14E, thecross-section of the frustopyramidal aspect of the inner surface of thetop collar wall increases in the downstream direction. Thus, corners45C, 45A emerge in cross-sectional view in FIG. 14C and become even moreprominent in FIGS. 14D, 14E. On the other hand, because the grooves Gextend from secondary conduit outlets 44A, 44C in a direction parallelto the axis of the primary conduit, the curved surfaces 145A, 145Cremain static relative to the axis of the primary conduit and areeventually swallowed up by corners 45A, 45C.

For ease of manufacture, the intermediate collar 39A, top collar 39B,and main body 7 are typically machined separately and are fastenedtogether as described above. However, they may be formed in a singleintegral piece and later machined to form all of the necessarystructures.

In the counterflow embodiment for the lance of FIGS. 10, 11, 12A-12B,13A-13B, 14A-14D, and 15, a vacuum is supplied to the inlet 3A of one ofthe four secondary conduits. This creates a region of sub atmosphericpressure (crescent-shaped in cross-section) bounded by curved surface145A, jutting portions 145A′, 145A″, and a peripheral region of the jetin the vectoring space downstream of outlet 44A. Due to the pressuredifferential between this region of sub atmospheric pressure and thejet, the jet is deviated at an angle to the axis of the primary conduittowards curved surface 145A and corner 45A. Given a sufficient degree ofapplied vacuum, the jet will “attach” to the curved surface 145A andcorner 45A to produce a stable deviated jet. Similarly, application ofvacuum to an inlet 3C of another of the other secondary conduits willdeviate the jet towards curved surface 145C and corner 45C and attachgiven a sufficient degree of vacuum. When the vacuum is supplied to theinlet 3B of one of the two remaining secondary conduits, a region of subatmospheric pressure is created that is bounded by the frustopyramidalinner surface of the top collar wall at corner 45B, jutting portions145A′, 145C′, and a peripheral region of the jet. Similarly, applicationof vacuum to the inlet 3D of another one of the two remaining secondaryconduits will create a region of sub atmospheric pressure that isbounded by the frustopyramidal top collar wall inner surface at corner45D, jutting portions 145A″, 145C″, and a peripheral region of the jet.For a given flow rate of the first gas through a given lance, the degreeof vacuum may be adjusted in an empirical manner to determine andoptimal level.

In the counterflow embodiment of the lance of FIGS. 10, 11, 12A-12B,13A-13B, 14A-14D, and 15, it is believed that a peripheral portion ofthe jet intersects the jutting portions 145A′, 145A″, 145C′, 145C″ attangent points to prevent “cross-talk” of gas flows between varioussecondary conduit outlets 44A, 44B, 44C, 44D. By preventing cross-talk,a relatively lower degree of vacuum is needed to attain a desiredpressure differential between the jet and the region of sub atmosphericpressure at hand. The curved surfaces 145A, 145C are also believed tomore easily create the regions of sub atmospheric pressure adjacent theperipheral region of the jet in comparison to the top collar wall innersurface adjacent corners 45B, 45D. While the lance of FIGS. 10, 11,12A-12B, 13A-13B, 14A-14D, and 15 illustrates grooves G formed only incorners 45A, 45C, it is understood that similar grooves may be formed inthe top collar inner wall surface in corners 45B, 45D. Conversely, eachof the corners 45A, 45B, 45C, 45D may be grooveless.

In the co-flow embodiment for the lance of FIGS. 10, 11, 12A-12B,13A-13B, 14A-14D, and 15, a flow of the second gas is allowed through asecondary conduit and exits outlet 44A in between curved surface 145Aand corner 45A, jutting portions 145A′, 145A″ and a peripheral region ofthe jet. The pressures of the sources of first and second gases upstreamof the primary and secondary conduits are selected such that the staticpressure of the co-flow adjacent the jet is lower than of the jet. Thiscreates a pressure differential between the co-flow and the jet whichdeviates the jet towards the curved surface 145A and corner 45A. Given asufficiently great pressure differential, the jet “attaches” to thecurved surface 145A and corner 45A to produce a stable deviated jet.Similarly, if the flow of the second gas is instead initiated throughanother of the secondary conduit and exits outlet 44C, the jet isdeviated towards a respective curved surface 145C and corner 45C andattaches given a sufficiently high pressure differential. When the flowof the second gas is instead initiated through the appropriate one ofthe two remaining secondary conduits, it may exit outlet 44B in betweencorner 45B, jutting portions 145A′, 145C′ and a peripheral region of thejet and be deviated towards corner 45B and attach given a sufficientlygreat enough pressure differential. Similarly, a flow of the second gaswhich is instead initiated through the opposite of the two remainingsecondary conduits and exits outlet 44D between corner 45D, juttingportions 145A″, 145C″ and a peripheral region of the jet will cause thejet to be deviated towards corner 45D and attach given a sufficientlygreat enough pressure differential. One of ordinary skill in the artwill recognize that a sufficiently higher velocity of the co-flowingsecond gas adjacent the jet will create the pressure differentialnecessary for deviation of the jet. Because the flow rate of the firstgas is driven by the requirements of the reaction space and is typicallyfixed, for a given lance configuration, an operator may adjust thepressure of the second gas upstream of the secondary conduit in anempirical manner in order to achieve a desired velocity for the co-flowand thus a desired pressure differential.

Regardless of whether the lance of FIGS. 10, 11, 12A-12B, 13A-13B,14A-14D, and 15 is operated according to the counterflow or the co-flowembodiment, alternation of vacuum applied to, or flow of the second gasallowed through, the three secondary conduits will alternatingly deviatethe jet back and forth across a generally quadrilateral target area.

As best illustrated in FIGS. 16-18, another lance embodiment includes anintermediate collar 59A secured to a main body 57 with fastenersinserted through bores 11 and a top collar 59B secured to theintermediate collar 59A with fasteners inserted through bores S5. Aprimary conduit is formed in the main body 7 and extends along an axis.The primary conduit extends between an inlet 1 and outlet 52 includes anupstream straight section 52, a diverging section 54, and a downstreamstraight section 56. Four secondary conduits are formed in theintermediate collar 59A. The first secondary conduit extends between aninlet 53A and an outlet 54A, while the second, third, and fourthsecondary conduits correspondingly extend between inlets 53B, 53C, 53Dand outlets 54B, 54C, 54D. The top collar 59A includes a wall thatcircumferentially extends from and around the primary conduit outlet 12and secondary conduit outlets 54A, 54B, 54C, 54D and extends in adownstream direction to terminate in a beveled surface B5. The innersurface of the top collar wall is a frustoconical surface (surface of afrustum of a cone) and includes four sections 55A, 55B, 55C, 55D. Theinner surface of the top collar wall diverges in the direction of thejet along the axis of the primary conduit.

The top collar includes four axially distributed slots each one of whichextends through the side wall of the top collar and the top collar innerwall surface. The slots are sized to accommodate four dividers W1, W2,W3, and W4 which partially extend out of the slots at the side wall ofthe top collar and partially extend inwards from the top collar innerwall surface. The dividers W1, W2, W3, W4 also extend in a directionparallel to the divergence of the collar wall inner surface fromimmediately downstream of the primary and secondary conduit outlets 52,54A, 54B, 54C, 54D and up to the beveled surface B5.

Before the fluidic deviation according to the invention is initiated,the first gas exits the primary conduit outlet 12 as a jet along theaxis of the primary conduit. The inner wall surface of the top collar59B defines a vectoring space into which the jet can expand. Each of thesecondary conduits 54A, 54B, 54C, 54D is disposed adjacent to andimmediately upstream of a respective quarter portion 55A, 55B, 55C, 55Dof the inner wall surface of the top collar 39B. Each combination of twoof the four dividers W1, W2, W3, W4 and the quarter portion 55A, 55B,55C, 55D that they bound defines a vectoring sub-space into which thejet may be deviated according to the mechanism of the invention. Thus,one of the four vectoring sub-spaces is defined by the combination ofdivider W1, quarter portion 55B, and divider W2. For ease ofmanufacture, the intermediate collar 59A, top collar 59B, main body 7,and dividers W1, W2, W3, W4 are typically machined separately and arefastened together as described above. However, they may be formed in asingle integral piece and later machined to form all of the necessarystructures. Additionally, the dividers W1, W2, W3, W4 need not projectoutwardly from a side of the top collar 59B.

In the counterflow embodiment for the lance of 16-18, a vacuum issupplied to the inlet 53A of one of the four secondary conduits. Thiscreates a region of sub atmospheric pressure adjacent a peripheralregion of the jet in the vectoring space downstream of outlet 54A. Dueto the pressure differential between the region of sub atmosphericpressure and the jet, the jet is deviated at an angle to the axis of theprimary conduit and into the vectoring sub-space defined by divider W4,quarter portion 55A, and divider W1. Given a sufficient degree ofapplied vacuum, the jet will “attach” to the quarter portion 55A toproduce a stable deviated jet. Similarly, application of vacuum to aninlet 53B of one of the other secondary conduits will deviate the jetinto the vectoring sub-space defined by divider W1, quarter portion 55B,and divider W2. The jet may be deviated into either of the othervectoring sub-spaces in a similar manner. The jet will also attach tothe respective quarter portion 55A, 55B, 55C, 55D given a sufficientdegree of vacuum. For a given flow rate of the first gas through a givenlance, the degree of vacuum may be adjusted in an empirical manner todetermine and optimal level.

In the co-flow embodiment for the lance of FIGS. 16-18, a flow of thesecond gas is allowed through a secondary conduit and exits outlet 54A.The pressures of the sources of first and second gases upstream of theprimary and secondary conduits are selected such that the staticpressure of the co-flow adjacent the jet is lower than that of the jet.This creates a pressure differential between the co-flow and the jetwhich deviates the jet into the vectoring sub-space defined by dividerW4, quarter portion 55A, and divider W1. Given a sufficiently greatpressure differential, the jet will attach to quarter portion 55A toproduce a stable deviated jet. Similarly, if the flow of the second gasis instead initiated through another of the secondary conduits and exitsoutlet 54B, 54C, or 54D, the jet is deviated into a respective vectoringsub-spaces defined by the various combinations of dividers W1, W2, W3,W4 and quarter portions 55B, 55C, 55D. One of ordinary skill in the artwill recognize that a sufficiently higher velocity of the co-flowingsecond gas adjacent the jet will create the pressure differentialnecessary for deviation of the jet. Because the flow rate of the firstgas is driven by the requirements of the reaction space and is typicallyfixed, for a given lance configuration, an operator may adjust thepressure of the second gas upstream of the secondary conduit in anempirical manner in order to achieve a desired velocity for the co-flowand thus a desired pressure differential.

Regardless of whether the lance of FIGS. 16-18 is operated according tothe counterflow or the co-flow embodiment, alternation of vacuum appliedto, or flow of the second gas allowed through, the four secondaryconduits will alternatingly deviate the jet back and forth across agenerally quadrilateral target area.

While FIGS. 2A-18 illustrate that the inlet of the secondary conduit ispositioned on a side of the collar, it can be positioned anywhere on thecollar including a position near the inlet of the primary conduit on oradjacent the main body.

Application to Metallurgical Furnaces

When the lance is utilized with a reaction space comprising an EAF, 1-10lances according to the invention can be used in order to increase foamyslag generation. The invention may be applied to metallurgical vesselsother than EAFs in which case it may be used to inject inert gases, inparticular, Argon or Nitrogen. Many of such vessels exhibit poor mixingbehavior that may be alleviated with supersonic injection of an inertgas jet via the invention for the purpose of stirring a relatively largearea of the bath contained therein.

When the lance is used to inject oxygen into an EAF, it may serveseveral different functions depending upon which stage the metallurgicalprocess is in: 1) melting, 2) beginning of the refining, 3) first halfof refining, and 4) last half of refining. During the melting phase, thedynamic lance is used as a classical supersonic lance without deviationof the jet. The oxygen flowing in the lance is used as complementaryoxygen for combustion or for post-combustion. During the beginning ofthe refining, the lance is used in supersonic mode for scrap cutting andfor initiating the refining. The lance may be swept in a pattern at arelatively low frequency (typically one degree per second) in order toget an efficient cut of the scrap. It may be desirable to avoid afrequency that is too slow such that the cavity opened up by the lanceat one location on the surface of the bath is allowed to completelyclose over before the jet is swept back to that location. It is duringthe beginning of the refining, that vertical deviation of the lance beaccomplished in order to achieve a more optimal angle of attack (i.e., amore vertical angle). The lance could also be used as a classical lanceas well. During the first half of refining, the lance could behorizontally and/or vertically swept in a regular pattern for increasingbath area coverage for greater refining efficiency. During the last halfof refining, the jet could be horizontally and/or vertically swept at arelatively higher frequency in order to promote better stirring andincrease the foamy slag quality.

Some basic techniques applying the invention to an EAF are illustratedin FIGS. 18 and 19. The EAF 100 includes electrodes 110 which createhotspots 120. A plurality of supersonic lances 130 inject oxygen acrossa target area described by an arc sweeping across an angle θ. Throughappropriate selection of the number and placement of the lances 130, arelative large area of the bath 140 in the EAF 100 can have oxygeninjected therein. As best shown in FIG. 18, the lances 130 may be sweptin a horizontal pattern. As best illustrated in FIG. 19, the lances 130may be swept in a vertical pattern. As described above, combinations ofvertical and horizontal sweeping are also possible.

The invention yields several advantages. When applied to metallurgicalfurnaces. It helps to reduce the tap-to-tap time through an increase inthe bath area coverage. It also achieves better stirring of the bath. Itfurther allows achievement of an optimal angle of attack. It allowsdynamic control of the lance without subjecting moving parts tocorrosive furnace gases and temperatures. The sweeping motion of the jetalso prevents the localized generation of FeO caused by the oxidizationof steel. It is well known that FeO is very corrosive to refractories sothe sweeping motion will reduce the localized concentration in the slag.Thus, it reduces O2 waste and improves metal yield.

EXAMPLES

Several different supersonic-type lances were constructed based uponsome of the above designs. Their ability to deviate a jet was testedunder the following counterflow conditions. The jet flow rate wasmaintained around 400 Nm³/h (i.e. 400 normal cubic meters per hour) witha Mach number around 2.1. A flow rate for the counterflow was maintainedat around 1 Nm³/h with a vacuum pressure of about 0.5 bar.

Lance design #1 was based upon the lance of FIGS. 16-18. Lance design #2was based upon the lance of FIGS. 16-18 but instead of a convergingnozzle for the primary conduit, a converging-diverging nozzle was used.Lance design #3 was based upon the lance of FIGS. 2A, 2B, 2C, 3, and 4.Lance design #4 was based upon the lance of FIGS. 10, 11, 12A-12B,13A-13B, 14A-14D, and 15 where no grooves were formed adjacent to thecorners. Lance design #5 was based upon the lance of FIGS. 10, 11,12A-12B, 13A-13B, 14A-14D, and 15 this time with grooves formed adjacentto the corners. Lance design #6 was based upon a design illustrated inFIGS. 21-24 that includes an intermediate collar between the bottom andtop collars that was designed to allow expansion of the jet before fluidcontact with a counterflow vacuum stream. Lance design #7 was based uponthe lance of FIGS. 7-9.

As shown in Table I, each lance design achieved a deviation angle of atleast 5°. The third and fifth designs were found to have achieved thelargest angle. Regardless of the lance design, we observed at most onlyabout a 20% decrease in coherence using Schlerin techniques.

TABLE I Deviation Angles Achieved By Various Lance Designs Design No.Result 1 10° 2  5° 3 15° 4 12° 5 15° 6  5° 7 10°

Preferred processes and apparatus for practicing the present inventionhave been described. It will be understood and readily apparent to theskilled artisan that many changes and modifications may be made to theabove-described embodiments without departing from the spirit and thescope of the present invention. The foregoing is illustrative only andthat other embodiments of the integrated processes and apparatus may beemployed without departing from the true scope of the invention definedin the following claims.

1. A method of injecting a jet of a gas into an interior of a reactionspace containing a liquid or solid reactant, said method comprising thesteps of: providing a lance comprising a main body having a primaryconduit and a secondary conduit formed therein and upstream anddownstream ends, each of the primary and secondary conduits extendingbetween a respective inlet and a respective outlet, the outlets beingdisposed at the downstream end, an outlet of the secondary conduit beingdisposed at a location adjacent the primary conduit outlet; injecting ajet of a gas from the outlet of the primary conduit and into thereaction space; and applying a vacuum to the secondary conduit to createa counterilow of a gas into the secondary conduit outlet from thereaction space interior and to cause deviation of the jet towards thecounterflow.
 2. The method of claim 1, wherein the jet has a velocitywith a Mach number in a range of from 0.3 to 5.0.
 3. The method of claim1, wherein the jetted gas is oxygen.
 4. The method of claim 1, whereinthe jetted gas is oxygen-enriched air.
 5. The method of claim 1,wherein: the primary conduit extends along an axis; the jet is deviatedby an angle θ with respect to the axis; and θ is in the range of0°<θ≦45°.
 6. The method of claim 1, further comprising the step ofdiscontinuing said application of vacuum such that the jet is no longerdeviated towards the counterflow.
 7. The method of claim 6 wherein saidsteps of applying and discontinuing application of the vacuum arealternated such that the jet is swept along an area described by anangle θ in the range of 0°<θ≦45°.
 8. The method of claim 1, wherein: thelance has a plurality of secondary conduits each one of which extendsbetween a respective inlet and a respective outlet, each of thesecondary conduit outlets being disposed at the downstream end; andapplication of vacuum is alternated between the plurality of secondaryconduits to alternatingly deviate the jet towards different ones of theplurality of secondary conduits.
 9. The method of claim 8, whereinalternating application of the vacuum between two of the secondaryconduits has the effect of sweeping the jet over an angular deviation offrom about −45° to about +45°.
 10. The method of claim 1, wherein thejet is supersonic.
 11. The method of claim 1, wherein the jet has a flowrate of 200 Nm³/h to 4000 Nm³/h.
 12. The method of claim 1, wherein aratio of the static pressure of the counterflow to the static pressureof the jet at the primary and secondary conduit outlets is in a range offrom 0.01 to less than 1.00.
 13. The method of claim 1, wherein thelance further comprises a collar extending from the downstream end ofthe main body, the collar having a continuous wall extending around theprimary and secondary conduit outlets, an inner surface of the walldefining a vectoring space, wherein the jet attaches to the innersurface adjacent the secondary outlet when the vacuum is appliedthereto.
 14. The method of claim 1, wherein: the lance has n secondaryconduits each one of which extends between a respective inlet and arespective outlet, each of the secondary conduit outlets being disposedat the downstream end; application of vacuum is alternated between the nsecondary conduits to alternatingly deviate the jet between a respectiven counterflows; and n is an integer in the range of from 2-6.
 15. Themethod of claim 14, wherein the jet is swept across a straightline-shaped target area.
 16. The method of claim 14, wherein the jet isswept across a triangular target area.
 17. The method of claim 14,wherein the jet is swept across a quadrilateral target area.
 18. Themethod of claim 1, wherein the reaction space is an electric arcfurnace.
 19. The method of claim 1, wherein the reaction space is amolten bath of non-ferrous metal.
 20. The method of claim 1, wherein asource of the vacuum is selected from a vacuum pump, an ejector pump,and a diverging portion of a converging-diverging nozzle.
 21. The methodof claim 1, wherein the jet is ideally expanded.
 22. The method of claim1, wherein the jet is under-expanded.
 23. The method of claim 1, whereinthe reaction space is a Basic Oxygen Furnace (BOF) or a top and bottommixed blown (QBOP) converter.
 24. The method of claim 1, wherein thereaction space is an Argon Oxygen Decarburization (AOD) furnace.
 25. Themethod of claim 1, wherein the reaction space is a Vacuum OxygenDecarburization (VOD) furnace.
 26. The method of claim 1, wherein thereaction space is a molten matte of sulfides of non-ferrous metals. 27.The method of claim 14, wherein: the lance has a plurality of secondaryconduits each one of which extends between a respective inlet and arespective outlet, each of the plurality of secondary conduit outletsbeing disposed at the downstream end; the vacuum is applied to one ofthe plurality of secondary conduits; and either a positive flow or noflow of a gas is simultaneously allowed through another of the pluralityof secondary conduits.
 28. The method of claim 1, wherein the jet has acircular cross-section.
 29. A system for injecting a jet of a gas intoan interior of a reaction space containing a liquid or solid reactant,comprising: a lance comprising a main body having a primary conduit anda secondary conduit formed therein and upstream and downstream ends,each of the primary and secondary conduits extending between arespective inlet and a respective outlet, the outlets being disposed atthe downstream end, an outlet of the secondary conduit being disposed ata location adjacent the primary conduit outlet; a source of a first gasat higher than ambient pressure fluidly communicating with the primaryconduit; and a source of a vacuum in selective fluid communication withthe secondary conduit.
 30. The system of claim 29, wherein the source ofthe vacuum is selected from a vacuum pump, an ejector pump, and adiverging portion of a converging-diverging nozzle.
 31. The system ofclaim 29, wherein the lance further comprises a collar extending fromthe downstream end of the main body, the collar having a wall extendingaround the primary and secondary conduit outlets, an inner surface ofthe wall defining a vectoring space through which a jet of the first gasmay be injected from the outlet of the primary conduit.